Electric system



Jan. 18, 1955 K. J. GERMEsHAUsEN 2,700,120

` ELECTRIC SYSTEM Filed March s. 1947 'I'III" /V VE N TOR #mwN/1 .zGMMEJHAc/ffa/ EilECT-C SYSTEM Kenne-eth1; Germeshausen; NewtonCenten'Mss.

Applicntiomliarch 3, llll, SeriallNo: `72'2",113.

9 Claimsf. @LSH- 18% The .present invention, though having -ields of..more general.; usefulness.Y in electric. systems, is...par1ticularlyrelated tosystems inzwhieh 'a flash. condenser. is: discharged. through;the gaseous-'mediumy of a. gaseous-discharge de'- vice forv suchfApurposes asto producefa.single..flash.or.a-l repetitionof flashes in.flash-photography ,and stroboscopic work...

The most ecientzliash-producers: ot: thenabovefdescribed character in:use: :today embodwashlamps-- com-.- monly called, ashtubes, .providedwith-.notonly an anode electrode. andacathode Aelectrode betweenwhichVto send' the.1tlash.producing .current..througl1=.the gaseousfmedium,hut.also..a high-voltage. starting, control .ort trigger .-.elec..trodez. The necessity-4 for.y employing .the trigger electrodeintroducescomplexities and increases-.the` sizeo the gaseous-discharge device,`but the proposals that have heretofore been made for eliminating it havenot been satisfactory.

An object of the present invention, therefore, to provide 'a new and'.improved electricisystern. of Ithe above'- d'escribed characterembodying;a.twoelectrode gaseousdischarge device.

Another object is to provide a new and'improved ash-producing systemofj'thefabove-described character embodyinga flash. .device unprovided.with a: starting; or controlelectrode.

Afurther 'object' i'sto provide. a. newv and improved.condenser-discharge, circuit .ofthe above-.describedSchar.-` acterlavinga three-electrode triggeringoparkgap; gaseous-discharge device in.serieszwith' the. gaseousrdisch'arge. tube.

Another .Objectisto provide anew.-and.improved. yelectric-.system of.thev above-described` character in..which` the discharge. .of acondenser -through a two-electrode gasa cous-discharge device is underthe .control offa. threeelectrode spark gap.

Another object stills to reduce theexpense ot vsystems of theabove-'described character.

Otherand further objects. will be explained hereinf` after; and will beparticularl'yp'ointed outiinxthe. appended claims.

The invention will'now be more fullyV explained.. in connection with theaccompanying drawings, in. which Figgl'is azdiagrammatif.:V view ofcircuits' and apparatus arranged and? constructed according to oneAembodiment of the invention; and Fig., .2 is asimilar view of a lmodication:

A .main-discharge flash condenser or capacitor. 11,. shownA .chargedfrom .a direct-current source, ,illustrated as 4al battery 19;. throughva` current-Limitingcharging; impeda'nce 12,4 is. showntseriesconnectedLin a discharge cir.- cuit'tothe anode electrode 7` 'and thecathodeelectr'odet 9 of a normally .non-conductingtwo-electrode gaseous'dischargedevice, such'as 'a space-'discharge'.ashtube or shl'amprl..`The condenserl 1I rnay be charged to a' voltagetor. from'ZOOf to2000'volts.; The'ashes -are pro# ducedby" dischargingihecondenser 11,after itLhas. become charged, throughlthe dischargecircuit and throughthe gaseous medium of thelamp `18,l between `the .anode 7'-'and thecathode 9."

The'three electrodes ofthe sparklgap gaseous-dischargev device vareshown comprising two principal electrodes 104 and 106-1and astart`ing,';triggering or'control electrode 150. l'nair, `thedistancebetween the principal electrodes 10.4 tand" 1(1'6 may be, say,.il/1g toA of' an inch. The spark gapl willfthen bezof vervlowimpedancecompared to the .severalfohms impedance of .'typical.fash.. lamps;

2.. As the energylost in the spark gapitself .is negligible; thisinsures that the .energy shallbe dissipatedin the ashlamp18..

One of the terminals of the condenser llfis connected permanently to.oneof. thev electrodes of thegaseousfdischargev device 18,. theotherterminalofthercondenser 11. is connected permanently tonne.of..the.principal electirodes of. the sparklgap, and theother.electrodeoffthe: gaseous-.discharge device 13.is connected permanentlytoy the other principal electrodel ot. the .spark..gap..l

Because .of the. dielectric properties. of the normally deionized airinthe space between the spark-gap electrodes. 1041-.and 1,06, thedirectfcurrent source 1i) will. charge the condenser .11 through theimpedance 12 .without :any of. its energy traversing thatspace.. A.difference of potentialwill therefore besestablished between. thespark-gapelec-` trodes 104 and 106 during thechargingofnthe condenser 11before each Hash. The impedance.12.should-be'de signed sutiicientlylarge so that, afterthe: creation.of. the spark between the principalelectrodes. 104 and..106,. further current ow between. them..will be.prevented. untilV after the air of the. spark .gap sha-ll haVeagan.become. deionized. T he-i1npedance 1-2 should,.ho.wever,v befsmall'.enough to permit of the condenser 11 becoming recharged. with'energyfrom the 4direct-current source l0 .in'tirnefor the next. tiash.

Referringnow more particularly to Fig..1,; the principal: electrodes 104and 1416 are shownconnected. in the con. denser-discharge. circuit,.. inseries; with. .the flashlamp. 18 The. principal..electrode 41G4- isshown...connected=.to the. anodel 7, and the principal electrode 106 toafterminal-19 connecting one' side of the condenser 11. to the. current?limiting impedance. 12.

The secondary winding. 15 of. a triggering v.transformer 14 is shown`connected to .the startingelectrode 15.0... A. high-voltagepulseisdesigned to be impressed .mornen.. tarily upon the.sec'ondaryfwinding 15at asuitable time,A intorderto impress a high-potentialstimulus .orchargeon the triggering electrode 151B.` The air in the'vicinity .ofthestartingelectrode 150, between. the. principal.. spark-gap electrodes.104 and 106, becomingtherebyrendered cone ducting, byionizati'on, ahigh-voltage low-energy spark willfijumpacross between the principalsparkfgapfelect'rodes' 1(14. and. 106.

Upon the spark gap becoming thus ionized, the .voltage of .the.condenser 11/becomes impressed across thelamp 181 If the lamp 1S is sodesigned that. its-.,breakdown. voltage shall be less. than the voltageto which. the con-.- denser.11 hasbeen charged, the lamp 18 will berenderedconducting. Upon the.1amp-18 becomingtthus. conduct ing the.condenser 11 will suddently discharge there. through', between.` theanode .7 and the cathode 9..-

'Ih'e necessarily highpealedischarge currents are thus eirctive'ly`controlled. by a .simple inexpensive triggeringA three-electrode sparkgap, Asthe additional high-voltage triggerelectrodethat iscustomarily/.employed with. gaseous-discharge ashlamps is unnecessaryaccording to the present invention the'connections. become simplilied,and. itil becomes possible to Aemploy a gaseous-discharge device 18 ofsmaller size..

The momentary'voltage pulse for triggering the spark gapmaybeind'uced inthe secondary winding 15 by sup-l plyinga corresponding voltage. pulsefor energizingthe prnnarywinding 13 ofthe transformer. 14. This may -beeffected. in any desired. way, as by discharging, a. small..tripjcondenser. 40.' through the primary winding 13, in series Withfa.normally non-conducting trigger tube 1,-

bywvayof lead wires 30 and 31. Because of thenormallyl non-conductingcharacter of the trigger. tube 1, it provides a'normall'yopen switchingdevice. Theimpedanceof the lead wires 30 and.31 which may befairlyllong, should not be tooVv great compared to the irnpedanceof.the-pri marvwin'dinglS'. The condenserlt'may be of the order ot''Oflmicrofarad, compared. to the order of 10 microf'arads for the condenser11."k

Thel condenser 40 may be charged from any desired direct-current source,such as a bleeder resistor.. bleederresistor is shown rcomprising tworesistor sections 81'and; 82 connected inlseries across the battery 10to constitute`V a. voltage divider for adjusting` the voltageon.. the.Ycondenser 40`. Thev freeterminalofthe resistor 81..

The

is connected to the terminal 19, at one side of the condenser 11, andthe free terminal of the resistor 82 is connected to the other side ofthe condenser 11.

The trigger tube 1 should be of a type capable of passing high-peakcurrents. It may, for example, be of the normally non-conductingcold-cathode gaseous-discharge type illustrated and described in LettersPatent 2,185,189, 2,202,166 and 2,201,167, issued January 2 and May 2l,1940. It may comprise an evacuated glass envelope filled with a suitablegas, such as neon, or any of the noble gases, such as argon or helium.The tube 1 is shown containing several electrodes, namely, a solid coldcathode 2, an anode or plate 5, and one or more grids 4. As explained inthe said Letters Patent, the source of the electrons is a bright cathodespot on the surface of the cathode 2. The moment of discharge of thecondenser 40 through the primary winding 13 is controlled by thepotential on the grid 4 of the trigger tube 1. An impedance 24,illustrated as a resistor, is shown connected between the cathode 2 andthe grid 4, in parallel with terminals 20.

When it is desired to trigger the flashes of the lamp 18, a potential isapplied to the control-grid electrode 4 through the terminals 20. Thisresults in closing the said normally open switching device, and triggersthe tube 1 to enable the trip condenser 40 to discharge therethrough andthrough the primary winding 13. The voltage and the power necessary toeffect this result depend upon the design of the particular tube 1employed.

A high impedance 23. shunted across the flashlamp 18. insures that theresaall be no voltage across the lamp 18 until the spark gap is triggered.This impedance, which may be on the order of a megohm, is low comparedto the leakage resistance across the lamp 18 when it is non-conducting,but high compared to the impedance of the lamp 18. when it is ionized.

It is desirable to have the lamp dimensions and the gas pressure suchthat the breakdown voltage of the flashtube 18 shall be appreciablygreater than the voltage to which the discharge condenser 11 is charged,say, several times as great. It has been found that the lamp 18 thenconverts a greater proportion of the energy in the condenser 11 intouseful light.

In the system of Fig. 1 the breakdown voltage of the lamp 18 must beless than the voltage to which the condenser 11 is charged. In thesystem of Fig. 2, however, this limitation in lamp design is removed,which permits of the use of a more efficient lamp. In this Fig. 2, thethree-electrode spark gap is shown controlling one of the circuitsdisclosed in application, Serial No. 679,983,

filed June 28, 1946, embodying a saturable transformer 114. Thesaturable transformer 114 is shown comprising primary and secondaryinductance windings 113 and 115. One end of the winding 113 is connectedto one end of the winding 115 at a common terminal 21. The other end ofthe winding 115 is shown connected to the anode 7 of the lamp 18. Theother end of the winding 113 is shown connected to the cathode 9 of thelamp 18 through a condenser 140, shown connected in parallel with theimpedance 23. The voltages of both the primary and secondary windings113 and 115 of the transformer 114 are thus connected in series circuitwith the flashtube 18.

Since the secondary winding 115 of the transformer 114 isseries-connected in the condenser-discharge circuit. it is desirable. inorder to attain high eiciency and a discharge time that shall not be toolong, that its impedance be low with respect to the impedance of thelamp 1S at the time of discharge of the condenser 11. For a reasonabledischarge current in the tube 1. on the other hand. it is desirable thatthe impedance of the primary winding 113 be reasonably high at the timethat the triggering impulse is applied to the primary winding 113 andprior to the discharge of the condenser 11.

With a primary winding the eifective impedance of which is high at thetime of the discharge of the condenser 40, moreover, it is possible toarrange that the impedance of the lead wires 30 and 31 to thetransformer primary winding 113, which may be fairly long, shall not betoo great compared to the impedance of this primary winding 113. Therequired low impedance of the secondary winding 115, at the time of thedischarge of the condenser 11. and the rectuired high impedance of theprimary winding 113, at the time that the triggering impulse is appliedto the primary winding 113, prior to the disof thin silicon-steellamlnations.

charge of the condenser 11, may be attained by providing the transformer114 with an iron core that saturates at the time when the main condenser11 discharges through the transformer in response to the production ofthe triggering voltage across the secondary winding 115. It is becauseof the saturable character of the core of the transformer 114 that a lowimpedance is offered to the discharge of the condenser 11l through thedischarge circuit including the gaseous-discharge device 18. Thepermissible saturated inductance of the secondary winding 115 of thetransformer 114 may be computed from the wellknown equations governingthe transient behavior of a series-discharge circuit of resistance,inductance and capacitance.

The impedance of a typical ashlamp 18, for example, 30 centimeters longand 4 millimeters inside diameter, and filled with Xenon at 10centimeters pressure of mercury, may be 3 or 4 ohms. A typical condenser11 may be of l0 microfarads capacity. The transient in theseries-condenser discharge circuit comprising the condenser 11, thesecondary winding 115, the spark gap and the lamp 1S will depend on therelative proportions of the resistance, the inductance and thecapacitance.

The saturated inductance of the secondary winding 115 of the transformer114 may be as great as 40 microhenries without seriously affecting theduration of the flash or the peak current in the condenser-dischargecircuit. If the resistive component of the impedance of the secondarywinding 115 is low compared to 4 ohms, the efficiency will still begood, and the operation will be comparable to the operation that takesplace without the transformer 114. Under the above conditions, theoperation will be satisfactory so long as where L is the inductance ofthe condenser-discharge circuit, R is its resistance, and C is itscapacitance. In most practical cases, it is permissible to tolerate eventhe relation:

A typical transformer 114 may have a closed iron core of 0.094 squareinch cross section and 4 inches effective length, and may be constitutedof a good grade On this core may be wound a secondary winding 115 of 50turns and a primary winding 113 of 5 turns. When the iron core issaturated, the inductance of the primary winding 113 may be of the orderof 0.20 microhenry, and that of the secondary winding 115 of the orderof 20 microhenries. The saturated inductance of 20 microhenries for thesecondary winding 115 is well below the value 40 microhenries beforereferred to. When the iron core is not saturated, the inductance may be100 times as great, corresponding to a primary-winding inductance of 20microhenries.. Since ordinary cable has an inductance on the order of0.2 microhenry per foot, this value is large enough so as not to.introduce troubles due to the impedance of the lead wires.

One side of the condenser 11, as in the system of Fig. 1, is connectedto the terminal 19. The principal spark-gap electrode 104, however, isalso connected to the terminal 19, and the other side of the condenser11 is connected to the terminal 21 of the saturable transformer. Themain-discharge capacitor 11 is charged from the directcurrent source 10,not only through the current-limiting impedance 12, as in the system ofFig. 1, but also through the saturable-transformer winding 113 and theimpedance 23.

The starting electrode is shown in Fig. 2 as energized, in order toimpress a high-potential stimulus or charge therein, by the secondarywinding 38 of a highratio triggering transformer 36, which may be of thespark-coil type. The primary winding 74 is shown connected in serieswith the cathode 2.

As in the system of Fig. 1, the small trip condenser 40 dischargesthrough the primary winding 74 of the transformer 36, in series with thetrigger tube 1, and the moment of discharge of the condenser 40 throughthe primary winding 74 is controlled by the potential on the grid 4 ofthe trigger tube 1. A high-voltage pulse becomes thereupon momentarilytransmitted through the transformer 36 to the spark-gap electrode 150,which affects lioni/lation of the gas between the spark-gap elecsamonzotcondenser.1'40. ,The `condenser-=140..may be oftheiorder \'of:0..1microfarad compared to v1I)rmic'rofara'ds `for the fcondenser -11.Thisprevents any appreciable;` portion of "thefenergysin the condenser11-frombeing dissipatedJin the series circuit-comprisingthe.condenser11, the transformer, primarywinding "1'13,the"con'denser 140, and theAtriggeredtspark,.gap. .Theevoltageifsurge applied tto the primary`winding `113 .of the .transformer 114produces a high voltage in thesecondary winding 115. The voltages of both the primary and secondarywindings 113 and 115 of the transformer 114 are in series circuit withthe ashtube 18. The lamp 18 will break down and become conducting if thetotal applied voltage is sufficient in magnitude. The main-dischargecondenser 11 will then discharge through the spark gap, the ash-lamp 18and the secondary winding 115 of the transformer 114.

Since the impedance 23 is essentially in parallel with the flash lamp18, its value should be relatively high compared to the impedance of thelamp 18 during the time that the condenser 11 is discharging into theash lamp 18. O11 the other hand, the impedance 23 should not be toolarge, as this would tend to prolong the time required to recharge thecondenser 11.

In the system of both Figs. 1 and 2, the three-electrode spark gapisolates the ashtube 18 from the high directcurrent potentials of thecondenser 11, except at the instant of Hash. As these high-potentialelements may be completely enclosed at some distance from the lamp 18,the operator may be fully protected from these high potentials, exceptat the moment of discharge. The enclosure, not shown, for thesehigh-potential elements may be rendered sound-proof, in order to renderthe operation of the spark gap inaudible.

Further modifications will occur to persons skilled in the art, and allsuch are considered to fall within the spirit and scope of theinvention, as defined in the appended claims.

What is claimed is:

l. An electric system having, in combination, a gaseous-dischargedevice, a condenser, means for charging the condenser, a saturable-coreinductor, a spark gap, a discharge circuit for the condenser includingthe gaseousdischarge device, the inductor and the spark gap connected inseries, and means for impressing a voltage upon the spark gap ofmagnitude suflicient to cause the spark gap to become conducting,thereby impressing a voltage upon the inductor such that, when added tothe charge on the condenser, it will exceed the magnitude of thebreakdown voltage of the gaseous-discharge device, thereby to enable thecondenser to discharge through the discharge circuit.

2. A flash-producing system having, in combination, a ash device, acondenser, means for charging the condenser, a saturable-core inductor,a spark gap, a discharge circuit for the condenser including the ashdevice, the inductor and the spark gap, and means for impressing avoltage upon the spark gap of magnitude suicient to cause the spark gapto become conducting, thereby impressing a voltage upon the inductorsuch that, when added to the charge on the condenser, it will exceed themagnitude of the break-down voltage of the flash device, thereby toenable the condenser to discharge through the discharge circuit in orderto produce a flash.

3. An electric system having, in combination, a gaseous-dischargedevice, a condenser, means for charging the condenser, a saturable-coretransformer having a primary winding and a secondary winding, a sparkgap, a discharge circuit for the condenser including thegaseousdischarge device, one of the windings of the transformer and thespark gap connected in series, and means for irnpressing a voltage uponthe spark gap of magnitude sufcient to cause the spark gap to becomeconducting, thereby impressing a voltage upon the other winding to causea voltage to appear on the said one winding of magnitude such that, whenadded to the charge on the condenser, it will exceed the magnitude ofthe break-down voltage of the gaseous-discharge device, thereby toenable the condenser to discharge through the discharge circuit.

4. A hash-producing system having, in combination, a ash device, acondenser, means for charging the condenser, a saturable-coretransformer having a primary-windin-gzandzassecondaryawinding,aesparlqgap,zaadischarge circuitlforA,the'lcondensera including thefrash.- devicefnonec of the windings ofthe transformerfand theffsparkrgap, and means for impressing a voltageupon the spark gap of magnitude rsuicient .to f cause i the :spark ,-gap-:to become conducting, .thereby .impressing-.a voltageupon the otherwinding to cause` avoltage toappearv on*the said winding oftma'gnitude.such.that, whenadded-to the-.chargemn the condenser,..it will exceedthe.:magnitude ofzthebreakv'dowdvolta'ge.of the ash device, :therebytofenablelthe "condenser to discharge through '.the @discharge icircuiti in orderto produce a Hash.

5. An electric system, having, in combination, a gaseous-dischargedevice, a condenser, means for charging the condenser, a saturable-coreinductor, a three-electrode spark gap, a discharge circuit for thecondenser including the gaseous-discharge device, the inductor and twoof the electrodes of the spark gap, and means for impressing a voltageupon the third electrode of the spark gap of magnitude sufficient tocause the spark gap to become conducting, thereby impressing a voltageupon the inductor such that, when added to the charge on the condenser,it will exceed the magnitude of the break-down voltage of thegaseous-discharge device, thereby to enable the condenser to dischargethrough the discharge circuit.

6. An electric system having, in combination, a gaseous-dischargedevice, a condenser, means for charging the condenser, a saturable-coretransformer, a threeelectrode spark gap, a discharge circuit for thecondenser including the gaseous-discharge device, the transformer andtwo of the electrodes of the spark gap, and means for impressing avoltage upon the third electrode of the spark gap of magnitude suicientto cause the spark gap to become conducting, thereby impressing avoltage upon the inductor such that, when added to the charge on thecondenser, it will exceed the magnitude of the break-down voltage of thegaseous-discharge device, thereby to enable the condenser to dischargethrough the discharge circuit.

7. An electric system having, in combination, a gaseous-discharge devicehaving two electrodes, a condenser, means for charging the condenser, asaturable-core transformer having a primary winding and a secondarywinding each having two ends, one end of one of the windings beingconnected to one end of the other winding, the other end of the said onewinding being connected to one of the electrodes of the dischargedevice, the other end of the said other winding being connected to theother electrode of the discharge device, a three-electrode spark gap, adischarge circuit for the condenser including the gascous-dischargedevice, one of the windings of the transformer and two of the electrodesof the spark gap, and means for impressing a voltage upon the thirdelectrode of the spark gap of magnitude suicient to cause the spark gapto become conducting, thereby impressing a voltage upon the inductorsuch that, when added to the charge on the condenser, it will exceed themagnitude of the break-down voltage of the gaseous-discharge device,thereby to enable the condenser to discharge through the dischargecircuit.

8. An electric system having, in combination, a gascous-dischargedevice, a condenser, means for charging the condenser, a saturable-coreinductor, a three-electrode spark gap, a discharge circuit for thecondenser including the gaseous-discharge device, the inductor and twoof the electrodes of the spark gap, and means comprising agridcontrolled rectifier for impressing a voltage upon the thirdelectrode of the spark gap of magnitude suicient to cause the spark gapto become conducting, thereby impressing a voltage upon the inductorsuch that, when added to the charge on the condenser, it will exceed themagnitude of the break-down voltage on the gaseousdischarge device,thereby to enable the condenser to discharge through the dischargecircuit.

9. A Hash-producing system having, in combination, a gaseous-dischargeflash device, a condenser, means for charging the condenser, asaturable-core inductor, a threeelectrode spark gap, a discharge circuitfor the condenser including the flash device, the inductor and two ofthe electrodes of the spark gap, and means comprising a gridcontrolledrectifier for impressing a voltage upon the third electrode of the sparkgap of magnitude suicient to cause the spark gap to become conducting,thereby impressing a voltage upon the inductor such that, when added tothe charge on the condenser, it will exceed the magnitude ReferencesCited in the le of this patent UNITED STATES PATENTS Swart Oct. 26, 1937Edwards Jan. 3, 1939 Inman Oct. 31, 1939 10 Edgerton Jan. 9, 1940Bychinsky Nov. 19, 1940 8 McKesson Mar. 25, 1941 Edgerton Jan. 6, 1942Perrin May 1, 1945 Back Dec. 25, 1945 Schelleng Dec. 3, 1946 SchockleyMar. 4, 1947 Maxwell Dec. 2, 1947 Rochester Aug. 1, 1950 FOREIGN PATENTSGreat Britain June 3, 1925 France Sept. 15, 1941

